The present invention relates to a modified conjugated diene-based polymer, a polymer composition and a process for producing a modified conjugated diene-based polymer.
Tires for automobiles are required to have low rolling resistance, wet grip, etc. Various researches and studies have been made so far in order to achieve a good balance between low rolling resistance and wet grip which hitherto have been considered to have a trade-off relationship with each other.
Polymer compositions for use in production of tires for automobiles are also required to be excellent in low rolling resistance and wet grip. In the field of these polymer compositions, a tan δ balance of such a polymer composition is used as a barometer for tire performance: for example, a tan δ value of the polymer composition at a temperature of from 50 to 70° C. is used as a barometer for low rolling resistance, and a tan δ value of the polymer composition at 0° C. is used as a barometer for wet grip. A polymer composition which shows a larger tan δ balance (i.e., a ratio of a tan δ value at 0° C. to a tan δ value at a temperature of from 50 to 70° C.) is considered to be suitable as a polymer composition for tires (refer to Non-Patent Documents 1 and 2).